1. Field of the Invention
This invention relates to a pressure regulator for reducing an unregulated pressure of an introduced high-pressure gas and obtaining a predetermined regulated pressure, which pressure regulator is suitable for use in liquefied gas utilizing appliances, gas supply facilities, and the like, and particularly for stabilization of fuel supply to solid oxide type fuel cells (SOFC's) and solid polymer type fuel cells (PEFC's).
2. Description of the Related Art
Ordinarily, liquefied gases and ordinary high-pressure gases, which have been accommodated in, for example, gas cylinders, have very high unregulated pressures and cannot be utilized directly. Also, the unregulated pressures of the liquefied gases and the ordinary high-pressure gases fluctuate markedly due to factors, such as an ambient temperature and a residual gas quantity. Therefore, pressure regulators (or pressure governors) for reducing the pressures of the high-pressure gases have heretofore been utilized widely in liquefied gas utilizing appliances, gas supply facilities, and the like. The pressure regulators have structures, wherein a regulated pressure is detected by a diaphragm, a regulating valve capable of moving in accordance with a displacement of the diaphragm is operated such that the regulated pressure becomes equal to a predetermined pressure in cases where the unregulated pressure fluctuates, and the predetermined regulated pressure is thereby obtained. (A pressure regulator having the structure described above is described in, for example, Patent Literature 1.)
The pressure regulators having various structures designed in accordance with required operating ranges of unregulated pressures, required response characteristics, and required stability have been used in practice. In accordance with the quality required of the regulated pressure, one kind of a pressure regulator or a combination of several kinds of pressure regulators has heretofore been used, and the predetermined regulated pressure has thus been obtained.
Fundamental structures of ordinary pressure regulators will be described hereinbelow with reference to FIGS. 15A, 15B, and 15C. FIGS. 15A, 15B, and 15C are schematic views showing fundamental structures of ordinary pressure regulators. FIG. 15A is a schematic view showing a single-valve type pressure regulator. With reference to FIG. 15A, a pressure regulator 500 comprises a diaphragm 504, which partitions a region within a casing 501 into a pressure regulating chamber 502 and an atmospheric chamber 503. The pressure regulator 500 also comprises a gas introducing port 505, through which a high-pressure gas having a pressure before being regulated is introduced into the pressure regulator 500. The pressure regulator 500 further comprises a regulating valve 506, which is interlocked with the diaphragm 504. The regulating valve 506 opens and closes an aperture 506c, through which the gas introducing port 505 and the pressure regulating chamber 502 communicate with each other. The regulating valve 506 performs the operations for opening and closing the aperture 506c from the unregulated pressure side and thereby reduces and regulates the unregulated pressure to the regulated pressure. The pressure regulator 500 still further comprises a gas discharging port 508, through which the gas having the regulated pressure and having passed through the pressure regulating chamber 502 is discharged. The pressure regulator 500 also comprises a weight 509, which urges the diaphragm 504 toward the direction of opening of the regulating valve 506 and thereby sets the regulated pressure.
The pressure regulator 500 is based upon the detection of a pressure difference between the atmospheric pressure and the regulated pressure. Specifically, the force occurring from an area of the diaphragm 504 and the pressure difference between the atmospheric pressure and the regulated pressure acts toward the direction of closing of the regulating valve 506, and the gravity of the weight 509 acts toward the direction of opening of the regulating valve 506. In a state in which the force occurring from the area of the diaphragm 504 and the pressure difference between the atmospheric pressure and the regulated pressure and the gravity of the weight 509 are balanced with each other, the regulated pressure is kept at the set pressure. In cases where the pressure on the gas discharging side, i.e. the regulated pressure in the pressure regulating chamber 502, is higher than the set pressure, the diaphragm 504 is displaced toward the side of the atmospheric chamber 503, and the regulating valve 506 is operated in the direction that closes the aperture 506c. In cases where the regulated pressure in the pressure regulating chamber 502 is lower than the set pressure, the diaphragm 504 is displaced toward the side of the pressure regulating chamber 502, and the regulating valve 506 is operated in the direction that opens the aperture 506c. More specifically, the motion of the diaphragm 504 occurring from the detection of the aforesaid pressure difference between the atmospheric pressure and the regulated pressure is transmitted to the regulating valve 506, which is located on the gas introducing side, and the regulated pressure is kept at the predetermined pressure through the pressure regulation performed with the opening and closing operations of the regulating valve 506.
However, in the cases of the single-valve type pressure regulator 500 described above, a pressure loss occurs due to the gas stream flowing through the regulating valve 506, and the force that displaces the diaphragm 504 toward the side of the atmospheric chamber 503, i.e. the force acting in the direction that closes the regulating valve 506, arises excessively from the value of the pressure loss described above and the area of the regulating valve 506. As described above, the regulating valve 506 performs the operations for opening and closing the aperture 506c from the unregulated pressure side. Therefore, in cases where the unregulated pressure becomes high, the aforesaid excessive force acting in the direction that closes the regulating valve 506 becomes large. Accordingly, the problems occur in that, as the unregulated pressure becomes high, the regulated pressure becomes low little by little, and the gas stream is ceased with the passage of time.
FIG. 15B is a schematic view showing a duplex-valve type pressure regulator. With reference to FIG. 15B, a pressure regulator 600 comprises a diaphragm 604, which partitions a region within a casing 601 into a pressure regulating chamber 602 and an atmospheric chamber 603. The pressure regulator 600 also comprises a gas introducing port 605, through which a high-pressure gas having a pressure before being regulated is introduced into the pressure regulator 600. The pressure regulator 600 further comprises two regulating valves 606 and 607, which are interlocked with the diaphragm 604. The regulating valves 606 and 607 respectively open and close two apertures 606c and 607c, through which the gas introducing port 605 and the pressure regulating chamber 602 communicate with each other. The regulating valves 606 and 607 thus reduce and regulate the unregulated pressure to the regulated pressure. The pressure regulator 600 still further comprises a gas discharging port 608, through which the gas having the regulated pressure and having passed through the pressure regulating chamber 602 is discharged. The pressure regulator 600 also comprises a weight 609, which urges the diaphragm 604 toward the direction of opening of the regulating valve 606 and thereby sets the regulated pressure.
The two regulating valves 606 and 607 described above are located such that the regulating valve 606 performs the operations for opening and closing the aperture 606c, which communicates with the pressure regulating chamber 602, from the unregulated pressure side, and such that the regulating valve 607 performs the operations for opening and closing the aperture 607c from the regulated pressure side. Therefore, with the duplex-valve type pressure regulator 600, the force due to the pressure loss occurring at the regulating valve 606 and the force due to the pressure loss occurring at the regulating valve 607 act in reverse directions and cancel each other. Accordingly, the drop of the regulated pressure accompanying the increase in the unregulated pressure is capable of being compensated for, and the regulated pressure is capable of being kept at a predetermined pressure.
As described above, the duplex-valve type pressure regulator 600 has good performance. However, the duplex-valve type pressure regulator 600 has the problems in that the two regulating valves 606 and 607 cannot always be located appropriately. Even if the two regulating valves 606 and 607 are capable of being located such that the regulating valves 606 and 607 simultaneously come into contact with their valve seats, the pressure loss of the gas stream passing through the regulating valve 606 and the pressure loss of the gas stream passing through the regulating valve 607 cannot always be equal to each other. Therefore, it is not always possible to constitute the duplex-valve type pressure regulator 600 such that the force exerted by the unregulated pressure upon the regulating valve 606 and the force exerted by the unregulated pressure upon the regulating valve 607 are perfectly canceled with each other.
FIG. 15C is a schematic view showing a modified duplex-valve type pressure regulator. With reference to FIG. 15C, a pressure regulator 700 comprises a diaphragm 704, which partitions a region within a casing 701 into a pressure regulating chamber 702 and an atmospheric chamber 703. The pressure regulator 700 also comprises a gas introducing port 705, through which a high-pressure gas having a pressure before being regulated is introduced into the pressure regulator 700. The pressure regulator 700 further comprises a regulating valve 706, which is interlocked with the diaphragm 704. The regulating valve 706 opens and closes an aperture 706c, through which the gas introducing port 705 and the pressure regulating chamber 702 communicate with each other. The regulating valve 706 thus reduces and regulates the unregulated pressure to the regulated pressure. The pressure regulator 700 still further comprises a regulating member 707, which is constituted of an O-ring and undergoes sliding movement together with the regulating valve 706. The pressure regulator 700 also comprises a gas discharging port 708, through which the gas having the regulated pressure and having passed through the pressure regulating chamber 702 is discharged. The pressure regulator 700 further comprises a weight 709, which urges the diaphragm 704 toward the direction of opening of the regulating valve 706 and thereby sets the regulated pressure.
The regulating valve 706 performs the operations for opening and closing the aperture 706c, which communicates with the pressure regulating chamber 702, from the unregulated pressure side. The unregulated pressure coming from the gas introducing port 705 acts upon one surface of the regulating member 707, which is constituted of the O-ring. Also, the regulated pressure, which comes from the pressure regulating chamber 702 through an intra-plunger gas flow path 710, acts upon the other surface of the regulating member 707. The force due to the pressure difference between the unregulated pressure, which acts upon the one surface of the regulating member 707, and the regulated pressure, which acts upon the other surface of the regulating member 707, is exerted upon the regulating member 707. The force, which is thus exerted upon the regulating member 707, cancels the force occurring from the value of the pressure loss, which arises at the regulating valve 706, and the area of the regulating valve 706. Therefore, even if the unregulated pressure becomes high, the regulated pressure is capable of being kept at the predetermined pressure. With the modified duplex-valve type pressure regulator 700, the regulating member 707 (corresponding to the regulating valve 607 of the duplex-valve type pressure regulator 600 shown in FIG. 15B) is constituted of the O-ring capable of undergoing the sliding movement, and the problems with regard to the location of the two regulating valves 606 and 607 of the duplex-valve type pressure regulator 600 shown in FIG. 15B are thereby solved.
[Patent Literature 1]